Currently, the pavement inspection for roadway can be approximately categorized into two classes including the manual investigation and the automatic investigation. The manual investigation is performed in accordance with the requirements under ASTM D6433. When the manual investigation is being practiced, it requires two engineers cooperating with each other to perform the investigation. However, for the manual investigation, the measurements to the damage grade or damage type are obtained on the basis of visual estimations, so that the results thereof might readily be subjectively biased and artificial negligence may easily occur.
The automatic investigation utilizes the instruments capable to manifest characters of terrain, such as, a supersonic sensor, a laser sensor, a camera and a video camera, to collect data relevant to the pavement in situ. The physical samples in situ will be replaced by the captured digital data. The automatic investigation provides better inspecting results than that of the manual investigation.
However, most of the current automatic investigation for pavement, in particular to the method in combination with the image identification scheme to perform the pavement inspection by utilizing the camera or the videos camera to capture digital image data, will encounter difficulties as follow.
(1) The inspecting result is interfered by the sun light. When the inspection is performed in daytime, shadows projected by such as road trees, road lamps, wire poles and buildings onto the surface of roadway, will affect the quality of images. Not only causing the difficulties for image post-processing, but the shadows will also degrade the efficiency for inspection.
(2) The inspecting result is influenced by external lights. If the roadway inspection is performed under the circumstances where the luminosity of sunlight is insufficient, the light fixture, such as road lamps, vehicle illumination instruments and other exterior lightings, are usually adopted to enhance the visibility of roadway. However, the various light sources will cause issue that luminosity in the images is non-uniform.
(3) The inspecting result is influenced by the lane markings on the roadway. The lane marking does not belong to breakings, cracks or defects on pavement of the roadway, but it perturbs the image post-processing.
(4) The inspecting result is influenced by the dirty spots on the roadway. Although the dirty spots, such as oil stained, water stained and etc., do not belong to the breakings on pavement, the spots will cause the image hardly identified and easily misjudged.
In order to overcome the drawbacks in the prior art, an electronic device having a bi-stable display is thus provided. The particular design in the present invention not only solves the problems described above, but also is easy to be implemented. Thus, the invention has the utility for the industry.